TWI829502B - Torque sensor - Google Patents

Abstract

The present invention provides a highly accurate torque sensor that suppresses enlargement of the shape. The torque sensor includes: a fourth structure disposed between the first structure and the second structure; a fifth structure; a first strain sensor disposed in the fourth structure; and a second strain sensor. The detector is installed in the fifth structure. The fourth structure and the fifth connection part respectively include: a first connection part connected to one end of the first strain sensor or the second strain sensor; and a second connection part connected to the first strain sensor or one end of the second strain sensor. The other end of the second strain sensor; and the third connection part and the fourth connection part are disposed between the first connection part and the second connection part, and have a larger diameter than the first connection part and the second connection part. The rigidity of the lower part is lower.

Description

Torque sensor

Field of invention An embodiment of the present invention relates to a torque sensor provided on a joint of a robot arm, for example.

Background of the invention The torque sensor has a first structure that applies torque; a second structure that outputs torque; and a plurality of strain portions as beams that connect the first structure and the second structure, and in which these strains A plurality of strain gauges as sensor elements are arranged on the part. These strain gauges constitute a bridge circuit (see, for example, Patent Documents 1, 2, and 3). Prior technical literature

patent documents Patent Document 1: Japanese Patent Application Publication No. 2013-096735 Patent Document 2: Japanese Patent Application Publication No. 2015-049209 Patent Document 3: Japanese Patent Application Publication No. 2017-172983

Summary of the invention The problem to be solved by the invention The bridge circuit of the torque sensor must be configured to output a voltage for force in the torque direction and not to output a voltage for force in directions other than torque.

However, if the processing accuracy of the first structure, the second structure, and the strain portion decreases, or if the arrangement of the strain gauges deviates, the bridge circuit outputs a voltage for force in directions other than torque, making detection accurate. degree decreased. Therefore, generally speaking, it is enough to design the structure of the torque sensor so that it is easily deformed in the direction of torque and not easily deformed in directions other than torque. However, in this case, the torque sensor The shape of the container will become larger.

An embodiment of the present invention is to provide a highly accurate torque sensor that can suppress an increase in shape. means to solve problems

The torque sensor of this embodiment includes: a first structure; a second structure; a plurality of third structures connecting the first structure and the second structure; and at least one fourth structure. between the first structure and the second structure; and a strain sensor provided in the fourth structure, and the fourth structure includes: a first connection portion provided in the first structure, and One end of the strain sensor is connected; a second connection is provided on the second structure and connected to the other end of the strain sensor; and a third connection and a fourth connection are provided on the second structure. The first connection part and the second connection part have a lower rigidity than the rigidity of the first connection part and the second connection part. Invention effect

Embodiments of the present invention can provide a highly accurate torque sensor that can suppress an increase in shape.

Form used to implement the invention Hereinafter, embodiments will be described with reference to the drawings. In the diagram, the same symbols are attached to the same parts.

FIG. 1 shows an example of the torque sensor 10 to which this embodiment can be applied.

In FIG. 1 , the torque sensor 10 includes a first structure 11 , a second structure 12 , a plurality of third structures 13 , a fourth structure 14 , a fifth structure 15 , stoppers 16 and 17 . And cover 18.

The first structure 11 and the second structure 12 are formed in an annular shape, and the diameter of the second structure 12 is smaller than the diameter of the first structure 11 . The second structure 12 is arranged concentrically with the first structure 11, and the first structure 11 and the second structure 12 are connected by a plurality of third structures 13 serving as beam portions arranged radially. The second structure 12 has a hollow portion 12a, and wiring (not shown) passes through the hollow portion 12a, for example.

The first structure 11 is connected to, for example, a measured object, and the plurality of third structures 13 transmit torque from the first structure 11 to the second structure 12 . On the contrary, the second structure 12 may be connected to the measured object, and the torque may be transmitted from the second structure 12 to the first structure 11 through a plurality of third structures 13 .

The first structure 11, the second structure 12, and the plurality of third structures 13 are made of metal, such as stainless steel, but they may be used as long as sufficient mechanical strength can be obtained for the applied torque. Materials other than metal.

FIG. 2 shows a state in which the stoppers 16 and 17 of FIG. 1 are removed. The first strain sensor 19 and the second strain sensor 20 are provided between the first structure 11 and the second structure 12 . That is, as will be described later, one end portion of the first strain sensor 19 and the second strain sensor 20 is joined to the first structure 11, and the first strain sensor 19 and the second strain sensor 20 The other end is joined to the second structure 12 .

In addition, the first strain sensor 19 and the second strain sensor 20 are arranged in positions that are symmetrical with respect to the centers of the first structure 11 and the second structure 12 (the center of action of the torque). In other words, the first strain sensor 19 and the second strain sensor 20 are arranged on the diameter of the annular first structure 11 and the second structure 12 .

The thickness of the first strain sensor 19 and the second strain sensor 20 , that is, the thickness of the strain body described below, is thinner than the thickness of the third structural body 13 . The mechanical strength of the torque sensor 10 is set by the thickness or width of the third structure 13 . The strain body is provided with a plurality of strain gauges as sensor elements, and these sensor elements form a bridge circuit.

The stoppers 16 and 17 protect the first strain sensor 19 and the second strain sensor 20 from mechanical deformation, and function as a cover for the first strain sensor 19 and the second strain sensor 20 . The details of the stoppers 16 and 17 will be described later.

The first strain sensor 19 is connected to the flexible substrate 21 , and the second strain sensor 20 is connected to the flexible substrate 22 . The flexible substrates 21 and 22 are connected to a printed circuit board (not shown) covered by the cover 18 . The printed circuit board is provided with an operational amplifier or the like that amplifies the output voltage of a bridge circuit described below. Since the circuit configuration is not essential to this embodiment, description thereof is omitted. (First Embodiment)

3 and 4 are diagrams showing the first embodiment. The first strain sensor 19 and the second strain sensor 20, the flexible substrates 21 and 22, the cover 18, etc. are removed from FIGS. 1 and 2. , only the first structure 11, the second structure 12, a plurality of third structures 13, the fourth structure 14, and the fifth structure 15 are displayed.

The first embodiment is configured such that when a force is applied to the torque sensor 10 in a direction other than the torque direction Mz, particularly in the direction of the arrows Fz and Mx shown in the figure, the strain will not be concentrated on the torque sensor 10 . The strain bodies of the first strain sensor 19 and the second strain sensor 20 are a plurality of strain gauges serving as sensor elements.

Specifically, the fourth structure 14 and the fifth structure 15 are provided at positions that are symmetrical with respect to the centers of the first structure 11 and the second structure 12. The fourth structure 14 has a structure formed from the first structure. 11 continues to the recessed portion 14f of the second structural body 12, and the fifth structural body 15 has the recessed portion 15f that continues from the first structural body 11 to the second structural body 12. As will be described later, the first strain sensor 19 is arranged in the recessed portion 14f of the fourth structural body 14, and the second strain sensor 20 is arranged in the recessed portion 15f of the fifth structural body 15.

In addition, although the first embodiment shows the case of including two strain sensors, the first strain sensor 19 and the second strain sensor, the number of strain sensors may be three or more. In this case, it is sufficient to increase the number of structures according to the number of strain sensors.

Since the fourth structure 14 and the fifth structure 15 have the same structure, only the fourth structure 14 will be described in detail.

As shown in FIG. 5 , the fourth structure 14 has: a first connection part 14 a and a second connection part 14 b as joint parts, to which the first strain sensor 19 is joined; and a third connection part 14 c and a fourth connection part as beams. part 14d; and the opening part 14e, surrounded by the first connection part 14a, the second connection part 14b, the third connection part 14c and the fourth connection part 14d.

In other words, the fourth structure 14 is a beam having the opening 14 e provided between the first structure 11 and the second structure 12 .

The first connecting portion 14a extends from the first structural body 11 toward the second structural body 12 side. The second connecting portion 14b extends from the second structural body 12 toward the first structural body 11 side.

The third connection part 14c and the fourth connection part 14d, which are beams, are provided between the first connection part 14a and the second connection part 14b.

The length L1 of the third connection part 14c and the fourth connection part 14d is shorter than the length L2 (also shown in FIG. 1 ) of the third structure 13 as a beam. The width W1 of the third connection part 14c and the fourth connection part 14d in the torque (Mz) direction is narrower than the width W2 of the first connection part 14a and the second connection part 14b in the torque direction. The total width W1 of the fourth connection portion 14d is narrower than the width W3 (shown in FIG. 1 ) of the third structure 13 in the torque (Mz) direction. Therefore, the rigidity in the torque direction of the third connection part 14c and the fourth connection part 14d is lower than the rigidity in the torque direction of the first connection part 14a, the second connection part 14b, and the third structure 13.

Moreover, the thickness of the 3rd connection part 14c and the 4th connection part 14d in the Fz direction is equal to the thickness of the 1st structure, the 2nd structure, and the 3rd structure in the Fz direction. In addition, the total length L11 of the first connection part 14a, the length L12 of the second connection part 14b, the length L1 of the third connection part 14c and the fourth connection part 14d is equal to the length of the third structure 13. Therefore, the rigidity of the third connection part 14c and the fourth connection part 14d in the Fz direction becomes slightly smaller than the rigidity of the third structure 13 in the Fz direction.

That is, as shown in FIG. 6A described later, in the torque (Mz) direction, the first connection part 14a and the first structure 11 constitute the high rigidity part HS1, and the second connection part 14b and the second structure 12 constitute the high rigidity part HS1. Constructs high rigidity part HS2. In addition, in the torque (Mz) direction, the third connection part 14c constitutes the low rigidity part LS1, and the fourth connection part 14d constitutes the low rigidity part LS2.

In addition, the total length L11 of the first connection part 14a, the length L12 of the second connection part 14b, the length L1 of the third connection part 14c and the fourth connection part 14d is not limited to being equal to the length of the third structure 13 can also be unequal.

The first connection part 14a has the aforementioned recessed part 14f. The thickness of the recessed portion 14f is thinner than the thickness of the first to third structures 11, 12, and 13.

One end of the first strain sensor 19 is the recess 14f connected to the first connection part 14a, and the other end is the recess 14f connected to the second connection part 14b. Therefore, the first strain sensor 19 spans the opening 14e. As will be described later, the bottom of the recess 14f is located below the center of the thickness of the fourth structure 14, and the surface of the strain body constituting the first strain sensor 19 is consistent with the plane including the center of gravity of the structure. It is a structure formed by the first structure 11 , the second structure 12 , a plurality of third structures 13 , the fourth structure 14 , and the fifth structure 15 .

6A and 6B are diagrams schematically showing FIG. 5 . FIG. 6A shows a situation in which a force in the direction of torque (Mz) is applied to the torque sensor 10 . FIG. 6B shows a situation in which force other than torque (Fz, Mx ) is applied to the torque sensor 10 .

As shown in FIG. 6A , when a force in the torque (Mz) direction is applied to the torque sensor 10 , the third connection part 14 c and the fourth connection part 14 d which are the low rigidity parts LS1 and LS2 are deformed. This first strain sensor 19 (second strain sensor 20) deforms and can detect torque.

On the other hand, as shown in FIG. 6B , when a force in a direction other than torque (Fz, Mx) is applied to the torque sensor 10 , that is, the first structure 11 moves relative to the second structure 12 In the case of displacement in the direction of the arrow in the figure, the rigidity of the first connection part 14a and the second connection part 14b, and the rigidity of the third connection part 14c and the fourth connection part 14d are almost equal. Therefore, the total length L2 of the length L11 of the first connection part 14a, the length L12 of the second connection part 14b, and the length L1 of the third connection part 14c and the fourth connection part 14d can function as an effective length. Since the length L2 is longer than the length L1 of the third connection part 14c and the fourth connection part 14d, when a force in a direction other than torque (Fz, Mx) is applied, the first strain sensor 19 ( The deformation of the second strain sensor 20) occurs in the range of length L2, so that the strain will not be concentrated on the plurality of strain gauges serving as sensor elements as the strain body provided in the first strain sensor 19. This can prevent the detection accuracy of the first strain sensor 19 (the second strain sensor 20) from being reduced.

FIG. 7 is a diagram schematically showing the fourth structure 14 . Referring to FIG. 7 , the second moment of section (ease of deformation) of the fourth structure 14 and the conditions required for the fourth structure 14 (the fifth structure 15 ) will be described.

The high-rigidity portion HS2 of the fixed fourth structure 14 is represented by Js and the cross-sectional secondary moment when a force in the torque (Mz) direction is applied to the high-rigidity portion HS1, and Jw is represented by the cross-sectional secondary moment when a force in the torque (Mz) direction is applied. The quadratic moment of area when a force is applied to the low-rigidity parts LS1 and LS2 is expressed as Is. The quadratic moment of area when a force in a direction other than torque (Fz) is applied to the high-rigidity part HS1 is expressed as Iw. The secondary moment of area when a force in a direction other than the moment (Fz) is applied to the low rigidity portions LS1 and LS2.

The ratio of the cross-section quadratic moment of the high-rigidity portion HS1 in the torque (Mz) direction to the cross-section quadratic moments of the low-rigidity portions LS1 and LS2 is expressed by the following equation (1). Js/Jw　:(1)

The ratio of the secondary moment of area of the high rigidity portion HS1 in the direction other than the torque (Fz) to the secondary moment of area of the low rigidity portions LS1 and LS2 is expressed by the following equation (2). Is/Iw　:(2)

As long as the values of equations (1) and (2) are both "1", the cross-sectional secondary moments of the high-rigidity portion HS1 and the low-rigidity portions LS1 and LS2 will be equal, and deformation will not be concentrated on the low-rigidity portions LS1 and LS2. As long as the values of the equations (1) and (2) are larger than "1", the deformation will be more concentrated in the low rigidity portions LS1 and LS2.

When a force in the direction of torque (Mz) is applied, strain is concentrated on the plurality of strain gauges serving as sensor elements as the strain body provided in the first strain sensor 19, and any force other than torque is applied. In the case of a force in the direction of (Fz, Mx), in order to shift the concentration of strain away from the strain gauge, it is desirable that the deformation concentration (α) on one side is close to 1 (α→1) and the deformation concentration on the other side is The concentration degree (β) and the deformation concentration degree (α) are very large in comparison (β>>α).

As long as the force in the direction of torque (Mz) is applied, the deformation concentration of the low rigidity portions LS1 and LS2 is higher than the deformation concentration of the low rigidity portions LS1 and LS2 when the force in the direction other than the torque (Fz) is applied. If it is large, it will be easily deformed by force in the direction of torque, and will not be easily deformed by force in directions other than torque. That is, it is a condition required for the fourth structure 14 (the fifth structure 15) that the relationship shown in the following equation (3) holds. Js/Jw＞Is/Iw　:(3)

Specifically, FIG. 8A is a cross-sectional view along line VIIIA-VIIIA shown in FIG. 7 and shows an example of the dimensions of the high rigidity portion HS1. FIG. 8B is a cross-sectional view along line VIIIB-VIIIB shown in FIG. 7 , and shows an example of the dimensions of low-rigidity portions LS1 and LS2 .

As shown in FIG. 8A , when a force in a direction other than torque (Fz) is applied to the high-rigidity portion HS1 having a U-shaped cross-section, the cross-sectional secondary moment Is related to the axis N1-N1 is as follows: Show. Here, the axis N1 - N1 is an axis passing through the center of the high rigidity portion HS1 in the thickness direction.

As shown in FIG. 8C , generally speaking, when the dimensions of a structure having an L-shaped cross section and a structure having a U-shaped cross section satisfy the relationships b=B-a, h=e1-t, the structure having an L-shaped cross section The cross-section secondary moment Is of the structure is the same as that of the structure having a U-shaped cross-section, and is expressed by the following equation (4). Is＝(Be13-bh3+ae23)/3　:(4) Here, h=e1-t, e1＝(aH2+bt2)/(2(aH+bt)) e2＝H-e1

Therefore, when a force in a direction other than torque (Fz) is applied to the high-rigidity portion HS1 shown in FIG. 8A , the cross-sectional secondary moment Is related to the axis N1-N1 can be obtained by equation (4) out.

In addition, e1 is the position of the center of gravity in the elastic body structure composed of the first structure body 11, the second structure body 12, a plurality of third structures 13, and is half the thickness of the structure body. A structure formed by the fourth structure 14 and the fifth structure 15 . Therefore, the thickness H=12 becomes e1≒6. Therefore, it will become e2≒6.

When the dimensions shown in Fig. 8A are substituted into equation (4), the result becomes as follows. Is＝(Be13-bh3+ae23)/3 =(14×63-8×(6-5.8)3+6×63)/3 =1440

Furthermore, as shown in FIG. 8B , when a force in a direction other than torque (Fz) is applied to the low-rigidity portions LS1 and LS2 having a rectangular cross-section, the cross-sectional secondary moment Is related to the axis N2-N2 is as follows: Show. Here, the axis N2 - N2 is an axis passing through the center of the thickness direction of the low rigidity portions LS1 and LS2.

As shown in Fig. 8D, generally speaking, the cross-sectional secondary moment Iw' of a structure having a rectangular cross-section is expressed by the following equation (5). Iw’＝bh3/12　:(5)

When the dimensions shown in Fig. 8B are substituted into equation (5), the result becomes as follows. Iw’=2×123/12 =288

Since the low-rigidity portions LS1 and LS2 shown in FIG. 8B have two rectangular cross-sections, the cross-sectional secondary moment Iw in the direction other than the torque (Fz) related to the axis N2-N2 is expressed by the following equation (6) . Iw＝2×Iw’　:(6)

Therefore, the cross-sectional secondary moment Iw in the direction other than the torque (Fz) related to the axis N2-N2 becomes as follows. Iw=576

On the other hand, as shown in FIG. 8E , when a force in the direction of torque (Mz) is applied to the high-rigidity portion HS1 having a U-shaped cross-section, the cross-sectional secondary moment Js related to the axis N3-N3 is as follows: Show. Here, the axis N3 - N3 is an axis passing through the center of the high rigidity portion HS1 in the width direction.

As shown in FIG. 8G , generally speaking, when the dimensions of a structure with an I-shaped cross section and a structure with a U-shaped cross section satisfy the relationships b=B-a, h=H-2t, the structure with an I-shaped cross section The cross-section secondary moment of the structure is the same as that of the structure having a U-shaped cross-section, and is expressed by the following equation (7). Js＝(BH3-bh3)/12　:(7)

When the dimensions shown in Fig. 8A are substituted into equation (7), the result becomes as follows. Js＝(12×143-6.2×83)/12 =2479

Furthermore, as shown in FIG. 8F , when a force in the torque (Mz) direction is applied to the low-rigidity portions LS1 and LS2 having a rectangular cross-section, the cross-sectional secondary moment Jw′ related to the axis N4-N4 is as shown in FIG. 8D To illustrate, it is represented by the following formula (8). Here, the axis N4 - N4 is an axis passing through the center of the low rigidity portion LS1 in the width direction. Jw’＝bh3/12　:(8)

When the dimensions shown in Fig. 8B are substituted into equation (8), the result becomes as follows. Jw’＝12×23/12 =8

Since the low-rigidity portions LS1 and LS2 shown in FIG. 8F have two rectangular cross-sections, the cross-sectional secondary moment Jw in the direction of the torque (Mz) related to the axis N4-N4 is expressed by the following equation (9). Jw＝2×Jw’　:(9)

Therefore, the cross-sectional secondary moment Iw in the direction other than the torque (Fz) related to the axis N2-N2 becomes as follows. Jw＝16

Substitute the secondary moments of area Is=1440 and Iw=576 in the direction other than the torque (Fz) and the secondary moments of area Js=2479 and Jw=16 in the direction of the torque (Mz) obtained by proceeding as above. After the above equation (3), it becomes as follows, and it can be seen that the condition of equation (3) is satisfied. Js/Jw>Is/Iw 2479/16>1440/576 155>2.5

Therefore, it can be seen that the fourth structure 14 and the fifth structure 15 are easily deformed with respect to the force in the direction of the torque (Mz) and are not easily deformed with respect to the force in the direction other than the torque (Fz).

FIG. 8H shows the positional relationship between the recessed portion 14f and the first strain sensor 19 (strain body). As mentioned above, the bottom of the recessed portion 14f is located below the center H/2 of the thickness of the fourth structure 14 . Specifically, in order to position the surface of the strain body constituting the first strain sensor 19 on the plane CG including the center of gravity of the structure, the bottom of the recessed portion 14f is provided lower than the plane CG including the center of gravity of the fourth structure 14. The position corresponding to the thickness of the strain body is a structure formed by a first structure 11 , a second structure 12 , a plurality of third structures 13 , a fourth structure 14 , and a fifth structure 15 body. This position is a neutral plane and does not exert compressive or tensile forces on the strain body. Therefore, the strain in the bending direction of the strain body, that is, in the direction other than the torque (Fz), can be reduced. (Effects of the first embodiment)

According to the first embodiment, the fourth structure 14 provided with the first strain sensor 19 and the fifth structure 15 provided with the second strain sensor 20 include the first connection part 14a and the second connection part. 14b acts as a highly rigid portion with respect to the force in the direction of the torque (Mz) and the direction other than the torque (Fz, Mx); and the third connection portion 14c and the fourth connection portion 14d act as a high-rigidity portion with respect to the torque ( The force in the direction Mz) acts as a low-rigidity portion, and the force in directions other than torque (Fz, Mx) acts as a high-rigidity portion. Therefore, it is possible to prevent strains caused by forces in directions other than torque from being concentrated on the strain gauges 51 , 52 , 53 , and 54 of the first strain sensor 19 and the second strain sensor 20 . Therefore, the absolute amount of strain applied to the strain gauges 51, 52, 53, and 54 can be reduced, and the strain of the first strain sensor 19 and the second strain sensor 20 in directions other than torque can be significantly reduced. Force detection voltage. Accordingly, it is possible to prevent the torque or other axes other than the torque from interfering, prevent the shape from being enlarged, and provide a highly accurate torque sensor.

Hereinafter, the effects of the first embodiment will be described in detail with reference to comparative examples.

FIG. 9 shows a comparative example of the torque sensor 10 . In the torque sensor 30 shown in FIG. 9 , the structure of the connection portion between the first strain sensor 19 and the second strain sensor 20 is different from the torque sensor 10 shown in the first embodiment. The structure is the same as that of the first embodiment.

In the torque sensor 30, one end portions of the first strain sensor 19 and the second strain sensor 20 are respectively connected to the protrusions 11-1 provided on the first structure 11, and the other end portions are respectively connected to the protrusions 11-1 provided on the first structure 11. It is connected to the protrusion 12-1 already provided in the second structure 12. The protrusions 11 - 1 and 12 - 1 have, for example, the same thickness as the first structure 11 and the second structure 12 . The distance between the protrusion 11-1 and the protrusion 12-1 is equal to the length L1 of the third connection part 14c and the fourth connection part 14d shown in FIG. 5 .

In the torque sensor 30 as a comparative example, only the third structure 13 acts as a highly rigid portion with respect to the force in the direction of the torque and directions other than the torque, and the first strain sensor 19 and the second strain sensor 30 function as a highly rigid portion. The sensor 20 only has a strain body provided between the first structure 11 and the second structure 12 . Therefore, when a force in the direction of the torque (Mz) is applied to the torque sensor 30 or when a force in a direction other than the torque (Fz, Mx) is applied, the strain will be concentrated in either direction. Strain gauges are provided on the strain bodies of the first strain sensor 19 and the second strain sensor 20 .

10A and 10B are diagrams schematically showing FIG. 9 . FIG. 10A shows a situation in which a force in the direction of torque (Mz) is applied to the torque sensor 30 . FIG. 10B shows a situation in which a force other than torque (Fz, Mx ) is applied to the torque sensor 30 .

FIG. 11 shows the distortion when the same force is applied in each axial direction of the torque sensor 10 of the first embodiment and the torque sensor 30 of the comparative example.

As can be clearly seen from FIG. 11 , in the case of the torque sensor 10 of the first embodiment, the strain with respect to the force in the direction of the torque (Mz) is larger than that in the comparative example. The strain of force in directions other than moments (Fx, Fy, Fz, Mx, My) will be smaller compared to the comparative example. In particular, it was found that the strain with respect to the force in the directions of Fz and Mx can be set to be significantly smaller compared with the comparative example. Therefore, according to the first embodiment, the strain caused by the force in the direction other than the torque can be reduced in the first strain sensor 19 and the second strain sensor 20, and the first strain sensor 19 and the second strain sensor 20 can be prevented from being strained. The detection accuracy of the second strain sensor 20 is reduced.

In addition, the surface of the strain body constituting the first strain sensor 19 is located on the plane CG including the center of gravity of the structure composed of the first structure 11 , the second structure 12 , and a plurality of third structures 13 , the fourth structure 14 , and the fifth structure 15 . Therefore, the strain in the bending direction of the strain body, that is, in the direction other than the torque (Fz), can be reduced. (Second Embodiment)

Fig. 12 shows the second embodiment.

As mentioned above, the first strain sensor 19 is provided in the fourth structure 14 , and the second strain sensor 20 is provided in the fifth structure 15 . Since the structures of the first strain sensor 19 and the second strain sensor 20 are the same, only the structure of the first strain sensor 19 will be described.

The first strain sensor 19 includes a strain body 41 and a plurality of strain gauges 51 , 52 , 53 , and 54 as sensor elements, which are arranged on the surface of the strain body 41 .

The strain body 41 is made of a rectangular metal plate, such as stainless steel (SUS). The thickness of the strained body 41 is thinner than the thickness of the third structural body 13 .

The strain gauges 51, 52, 53, and 54 are composed of thin film resistors such as Cr-N provided on the strain body 41. The material of the thin film resistor is not limited to Cr-N.

One end of the strain body 41 is connected to the first connection part 14a, and the other end is connected to the second connection part 14b. The strain body 41 may be connected to the first connection part 14 a and the second connection part 14 b by a connection method using, for example, welding, screwing, or adhesive.

The strained body 41 functions as a substantial strained body, for example, with a portion between the position welded to the first connection part 14a and the position welded to the second connection part 14b. Therefore, the effective length of the strain body 41 is equivalent to the length from the position connected to the first connection part 14a to the position connected to the second connection part 14b.

The plurality of strain gauges 51 , 52 , 53 , and 54 are arranged in the region AR1 on the second structural body 12 side of the center portion CT of the effective length of the strain body 41 in the strain body 41 . This area AR1 is an area where large strain occurs in the strain body 41 within the range of the opening 14e. As will be described later, this area AR1 is the sensitivity of the first strain sensor 19 with respect to the force in directions other than torque, such as the Fx and My directions, and the first strain sensing in the torque (Mz) direction. The sensitivity of detector 19 will become the same area.

The strain gauges 51 , 52 , 53 , and 54 are arranged in the area AR1 with the longitudinal directions of the strain gauges 51 , 52 , 53 , and 54 along the two diagonal lines DG1 and DG2 of the strain body 41 . That is, the strain gauges 51 and 52 are arranged with their long sides along one diagonal line DG1 shown by the dotted line, and the strain gauges 53 and 54 are arranged with their long sides along the other diagonal line shown by the dotted line. DG2 to configure. Diagonal lines DG1 and DG2 correspond to rectangular areas located within the opening 14e of the strain body 41.

The strain gauges 51, 52, 53, and 54 of the first strain sensor 19 constitute a bridge circuit, and the strain gauges 51, 52, 53, and 54 of the second strain sensor 20 also constitute a bridge circuit. Therefore, the torque sensor 10 is provided with two bridge circuits.

FIG. 13 shows an example of the bridge circuit 50 of the first strain sensor 19 . The second strain sensor 20 also has a bridge circuit having the same configuration as the bridge circuit 50 . The output voltage of the bridge circuit 50 of the first strain sensor 19 and the output voltage of the bridge circuit 50 of the second strain sensor 20 are each compensated for offset or temperature using software (not shown), for example. Thereafter, the output voltage of the bridge circuit 50 of the first strain sensor 19 and the output voltage of the bridge circuit 50 of the second strain sensor 20 are integrated and output as the detection voltage of the torque sensor 10 . Compensation for offset, temperature, etc. is not limited to software and can also be performed by hardware.

The bridge circuit 50 is a series circuit in which a strain gauge 52 and a strain gauge 53 and a strain gauge 54 and a strain gauge 51 are arranged in series between the power supply Vo and the ground GND. The output voltage Vout+ is output from the connection node of the strain gauge 52 and the strain gauge 53, and the output voltage Vout- is output from the connection node of the strain gauge 54 and the strain gauge 51. The output voltage Vout+ and the output voltage Vout- are supplied to the operational amplifier OP, and the output voltage Vout is output from the output terminal of the operational amplifier OP.

When a force in the direction of torque (Mz) is applied to the torque sensor 10, a number can be obtained from the output voltage Vout+ of the connection node on one side of the bridge circuit 50 and the output voltage Vout- of the connection node on the other side. The output voltage Vout of the torque sensor 10 shown in equation (5). Vout＝(Vout+-Vout-) ＝(R3/(R2＋R3)-R1/(R1＋R4))・Vo　　:(5)

Here, R1 is the resistance value of the strain gauge 51 , R2 is the resistance value of the strain gauge 52 , R3 is the resistance value of the strain gauge 53 , and R4 is the resistance value of the strain gauge 54 .

In a state where no torque is applied to the torque sensor 10, ideally, R1=R2=R3=R4=R. However, in reality, the resistance value varies, and in a state where no torque is applied, a voltage accompanying the variation in the resistance value is output. This voltage is set to zero by offset adjustment.

On the other hand, when a force in directions other than torque, such as Fx and My directions, is applied to the torque sensor 10 , the output resistance Vout can be output from the bridge circuit 50 due to changes in the resistance values of R1 to R4 . However, the output voltage of the bridge circuit 50 of the second strain sensor 20 outputs a voltage that is positive and negative opposite to the output voltage of the bridge circuit 50 of the first strain sensor 19 . Therefore, since the output voltages in each bridge circuit 50 have the same absolute value but different positive and negative values, they are offset and the detection voltage becomes 0V.

When the strain gauges 51, 52, 53, and 54 as sensor elements have the same displacement amount in the torque (Mz) direction and in the directions other than torque (Fx, My), it is ideal that the outputs are the same. voltage. Therefore, the strain gauges 51, 52, 53, and 54 are preferably disposed in a region where the strains of the strain body 41 are equal in the torque (Mz) direction and in directions other than the torque (Fx, My) (measured area where sensitivities are equal).

FIG. 14 schematically shows the state of the strain body 41 when a force in the direction of torque (Mz) is applied to the torque sensor 10 and when a force in a direction other than the torque (Fx, My) is applied. .

Macroscopically observing the operation of the strain body 41 installed between the first structure 11 and the second structure 12, when a force in the torque (Mz) direction is applied to the torque sensor 10, and when In any case where a force in a direction other than torque (Fx, My) is applied, it appears that the strain body 41 is changed in the shear direction.

However, when a force in the torque (Mz) direction is applied to the torque sensor 10 after microscopically observing the operation of the strain body 41 provided between the first structure 11 and the second structure 12, There will be a rotational force acting on the strained body 41. On the other hand, when a force in a direction other than torque (Fx, My) is applied to the torque sensor 10 , a translational force acts on the strain body 41 . Therefore, the deformation of the strain body 41 differs between when a force in the direction of the torque (Mz) is applied and when a force in a direction other than the torque (Fx, My) is applied.

That is, there is a difference between the deformation of the region AR1 of the strained body 41 on the second structural body 12 side and the deformation of the region AR2 of the strained body 41 on the first structural body 11 side. Specifically, in the area AR1 of the strain body 41 , the strain of the strain body 41 when a force in the direction of the torque (Mz) is applied, and the strain of the strain body 41 when a force in the direction other than the torque (Fx, My) is applied. The difference between the strain of the strain body 41 is the strain of the strain body 41 when a force in the direction of torque (Mz) is applied in the region AR2 of the strain body 41, and the strain of the strain body 41 when the torque (Fx, The difference in strain of the strain body 41 in the case of a force in the direction My) is smaller.

That is, in the area AR1 on the second structure 12 side, the strain of the strain body 41 when a force in the direction of the torque (Mz) is applied is different from the strain of the strain body 41 when a force in the direction other than the torque (Fx, My) is applied. In this case, the difference in strain of the strain body 41 is small.

Therefore, when a plurality of strain gauges 51, 52, 53, and 54 are arranged in the area AR1, the difference between the detection sensitivity of torque (Mz) and the detection sensitivity of other than torque (Fx, My) will be small, and there will be no Up to 1%. On the other hand, when a plurality of strain gauges 51, 52, 53, and 54 are arranged in the area AR2, the difference between the detection sensitivity of torque and the detection sensitivity other than torque is several percent. Therefore, it is preferable to arrange a plurality of strain gauges 51, 52, 53, and 54 in the area AR1 on the second structure 12 side. (Effects of the second embodiment)

According to the above-described second embodiment, the first strain sensor 19 and the second strain sensor 20 each include: a strain body 41 connected between the first structure 11 and the second structure 12; and as a sensor A plurality of strain gauges 51, 52, 53, and 54 of the strain gauge element are provided on the strain body 41, and the plurality of strain gauges 51, 52, 53, and 54 are arranged at a second position farther from the center CT in the longitudinal direction of the strain body 41. Area AR1 on the structure 12 side. The area AR1 of the strain body 41 is the strain (sensitivity) (a1, a2) when a force in the torque direction is applied to the first strain sensor 19 and the second strain sensor 20 respectively, and The difference in strain (sensitivity) (b1, b2) for forces in directions other than torque is a small area (a1≒b1, a2≒b2, a1≠a2). Therefore, by adjusting the sensitivity of the torque separately for the first strain sensor 19 and the second strain sensor 20, there is no need to rely on the first structure 11, the second structure 12, and the third structure. The processing accuracy of 13 or the arrangement accuracy of the first strain sensor 19 and the second strain sensor 20 relative to the first structure 11 and the second structure 12 can prevent the torque detection accuracy from being compromised. reduce.

Furthermore, since the difference in detection sensitivity of the bridge circuit 50 arranged in the area AR1 of the strain body 41 with respect to the force in the torque direction and the force in the direction other than the torque is small, the first strain sensor 19 and the second strain sensor The error of the output voltage of the detector 20 will also be smaller. Therefore, when correcting the voltages output from the two bridge circuits 50 , as long as the detection error with respect to torque is corrected, detection errors other than torque can also be corrected. Therefore, since there is no need to install another strain sensor for detecting forces in directions other than torque (Fx, My), correction time can be shortened and high-speed response can be achieved.

Hereinafter, the effects of the second embodiment will be described in detail.

FIG. 15 schematically shows the torque sensor 60 of the comparative example. This torque sensor 60 includes a first strain sensor 61 and a second strain sensor 62 between the first structure 11 and the second structure 12 . The first strain sensor 61 and the second strain sensor 62 each have a strain body 63. In each strain body 63, a plurality of strain gauges 51, 52, 53 constituting the bridge circuit shown in FIG. 13 are arranged. 54. Since FIG. 15 is a schematic diagram, the third structure 13 is omitted.

In the comparative example, the arrangement of the strain gauges 51, 52, 53, and 54 is different from that of the second embodiment. That is, the strain gauges 52 and 53 are arranged in the region of the strain body 63 on the first structural body 11 side, and the strain gauges 51 and 54 are arranged in the region of the strain body 63 on the second structural body 12 side.

In the case of the structure shown in FIG. 15 , the strain gauges 52 and 53 arranged in the area on the first structural body 11 side have the strain gauges 63 in the torque (Mz) direction and the directions other than the torque (Fx, My). The strains are different. Therefore, the sensitivity of the first strain sensor 61 and the sensitivity of the second strain sensor 62 when a force in the direction of torque (Mz) is applied are different from the sensitivity of the first strain sensor 62 when a force in a direction other than torque (Fx, My) is applied. In this case, the difference in sensitivity between the first strain sensor 61 and the second strain sensor 62 is large.

Specifically, when a force in a direction other than torque (Fx, My) is applied to the torque sensor 60, the sensitivity in a direction other than torque (Fx, My) is equal to that in the direction of torque (Mz). The sensitivities are different, so the value of the output voltage of the first strain sensor 61 (positive value) and the value of the output voltage of the second strain sensor 62 (negative value) are different from each other. Therefore, the torque sensor 60 outputs an error formed by the average value of the first strain sensor 61 and the second strain sensor 62 .

On the other hand, in the case of the torque sensor 10 of the second embodiment, when a force in a direction other than the torque (Fx, My) is applied to the torque sensor 10, the force in the direction other than the torque (Fx, My) The sensitivity in the direction of , My) is consistent with the sensitivity in the direction of torque (Mz). Accordingly, the output voltage value (positive value) (Vout1) of the first strain sensor 19 and the output voltage value (negative value) (-Vout2) of the second strain sensor 20 become almost equal to each other. (｜Vout1｜≒｜-Vout2｜). Therefore, the output of the torque sensor 10 is canceled by the output voltages of the first strain sensor 61 and the second strain sensor 62 and becomes almost zero. Therefore, in the case of the second embodiment, it is possible to reduce detection errors with respect to forces in directions other than torque (Fx, My).

In the case of the torque sensor 60 of the comparative example, in the torque (Mz) direction and the directions other than torque (Fx, My), the first strain sensor 61 and the second strain sensor 62 The error of the output voltage is large (|Vout1|≠|-Vout2|). Therefore, in order to correct these errors, it is necessary to correct the detection error in the correction torque direction and the detection error in directions other than the correction torque. Therefore, the torque sensor 60 of the comparative example must be provided with an additional bridge circuit including a strain gauge for detecting force in directions other than torque. Therefore, in the torque sensor 60 of the comparative example, the circuit board is enlarged or the calculation processing time of the software is increased. Compared with the second embodiment, the adjustment operation is complicated and the response performance is reduced.

On the other hand, in the case of the second embodiment, there are almost no first strain sensors 19 and second strain sensors 20 in the torque (Mz) direction and the directions other than torque (Fx, My). error of the output voltage. Therefore, it is only necessary to correct the detection error in the torque direction. Therefore, the correction time can be shortened, and the response performance of the torque sensor can be improved.

In addition, the second embodiment is not limited to the structure of the torque sensor 10, and the strain gauges 51, 52, 53, and 54 may be arranged in the area AR1. Therefore, even if the arrangement of the second embodiment is applied to, for example, the torque sensor 30 having the structure shown in FIG. 9 , the same effects as those of the second embodiment can be obtained. (Third Embodiment)

FIG. 16 is a diagram showing the third embodiment, in which the portion shown in B of FIG. 1 is enlarged and shown.

As explained with reference to FIG. 2 , the first strain sensor 19 is covered by the stopper 16 , and the second strain sensor 20 is covered by the stopper 17 . The stopper 16 and the stopper 17 are formed of, for example, stainless steel or iron-based alloy. The stoppers 16 and 17 prevent mechanical deformation of the first strain sensor 19 and the second strain sensor 20 and protect the strain gauges 51 , 52 , 53 , and 54 . Furthermore, the stoppers 16 and 17 serve as waterproof covers for the first strain sensor 19 and the second strain sensor 20 . Description of the specific waterproof structure is omitted.

Since the structures of the stopper 16 and the stopper 17 are the same, only the stopper 16 will be described.

As shown in FIG. 16 , the stopper 16 has one end 16 a and the other end 16 b. The width of the other end 16 b of the stopper 16 is narrower than the width of the one end 16 a. One end portion 16 a of the stopper 16 is, for example, press-fitted and fixed in a recessed portion 14 f formed on the second structural body 12 side of the fourth structural body 14 as an engaging portion. The other end portion 16 b of the stopper 16 is disposed in the recessed portion 14 f formed in the fourth structural body 14 on the first structural body 11 side. The width of the other end portion 16b of the stopper 16 is narrower than the width of the recessed portion 14f provided on the first structural body 11 side, and between both sides of the other end portion 16b of the stopper 16 and the side surfaces of the recessed portion 14f, respectively Gap GP is provided.

The gap GP is determined by the rigidity and rated torque of the third structure 13 .

Specifically, when a torque of, for example, 1000 N·m is applied to the torque sensor 10 and the first structure 11 is deformed by, for example, 10 μm relative to the second structure 12, the gap GP is set to, for example, 10μm.

17A and 17B are diagrams showing the operation of the stopper, and schematically show a part of FIG. 16 .

As shown in FIG. 17A , when torque is not applied to the torque sensor 10 , a predetermined gap GP is provided between both sides of the other end 16 b of the stopper 16 and the recess 14 f. In this state, when torque less than the rated torque is applied to the torque sensor 10, the first structure 11 moves relative to the second structure 12, and the first strain sensor 19 moves from the first strain sensor 19 to the second structure 12. Outputs a voltage corresponding to the applied torque. After the torque applied to the torque sensor 10 is removed, the first strain sensor 19 will recover by elastic deformation.

On the other hand, as shown in FIG. 17B , when a torque larger than the rated torque is applied to the torque sensor 10 , the side surface of the recess 14 f of the first structure 11 comes into contact with the stopper 16 The other end portion 16b restricts the movement of the first structure 11 relative to the second structure 12. Therefore, the first strain sensor 19 is protected within the range of elastic deformation. After the torque applied to the torque sensor 10 is removed, the first strain sensor 19 will recover by elastic deformation. The second strain sensor 20 is also protected by the same configuration.

FIG. 18 is a diagram for explaining the relationship between the torque as a load applied to the torque sensor 10 and the operation of the stopper 16 , and schematically shows the torque applied to the torque sensor 10 , and the relationship between the detected strain (the output voltage of the bridge circuit 50).

As shown in FIG. 18 , when torque less than the rated torque is applied to the torque sensor 10 , in the strain body 41 of the first strain sensor 19 (the second strain sensor 20 ), The first structural body 11 moves relative to the second structural body 12, and a voltage corresponding to the applied torque is output from the first strain sensor 19 (second strain sensor 20).

On the other hand, when a torque larger than the rated torque is applied to the torque sensor 10, the side surface of the recess 14f will come into contact with the stopper 16, and the rigidity of the stopper 16 (stopper 17) will The deformation of the plurality of third structures 13 is suppressed, and accordingly, the deformation of the strained body 41 is suppressed. That is, the operating point Op of the stopper 16 is set equal to the rated torque of the torque sensor 10 , and the stopper 16 protects the strain body 41 against a torque greater than the rated torque. (Effects of the third embodiment)

According to the above-described third embodiment, the first strain sensor 19 and the second strain sensor 20 are provided with the stopper 16 as a cover, and the one end 16 a of the stopper 16 is fixed to the recessed portion on the second structural body 12 side. In 14f, when a torque larger than the rated torque is applied to the torque sensor 10, the other end portion 16b comes into contact with the side surface of the recessed portion 14f on the first structural body 11 side. Therefore, the first strain sensor 19 and the second strain sensor 20 can be protected. Furthermore, structures other than the first strain sensor 19 and the second strain sensor 20 can also be protected from plastic deformation in the same manner as the first strain sensor 19 and the second strain sensor 20 . .

Furthermore, the rated torque of the torque sensor 10 can be made close to the 0.2% yield stress of the strain gauge. Therefore, the output voltage of the bridge circuit 50 at rated torque can be made larger. Therefore, a high-resolution, high-accuracy torque sensor can be provided.

19 is a diagram showing the relationship between strain and stress of the strain gauge, and shows the rated torque of the torque sensor of the third embodiment and the torque without the stopper 16 and the stopper 17 as a comparative example. Rated torque of the torque sensor.

In the case of a general torque sensor without stoppers 16 and 17 as a comparative example, the strain gauge is designed so that the safety factor against impact or fatigue is set to approximately 3 to 5. When the safety factor is set to 3, for example, the stress of the strain gauge is set to 1/3 of the 0.2% endurance. Therefore, the rated torque is also set to 1/3 of the breaking torque.

On the other hand, in the case of the third embodiment, since the first strain sensor 19 and the second strain sensor 20 can be protected by the stopper 16 and the stopper 17, there is no need to secure the strain gauge. The coefficient is set to 1 or more. Therefore, the rated torque of the strain gauge can be set to be larger than that of a general torque sensor without the stoppers 16 and 17 . Therefore, a high-resolution, high-accuracy torque sensor can be provided.

Furthermore, by increasing the rigidity of the stopper 16, a torque sensor with a high allowable load (high maximum torque) can be provided. (Modification)

FIG. 20 is a diagram showing a first modification of the third embodiment. In the third embodiment, the stopper 16 protects the first strain sensor 19 by contacting the other end 16 b with the side surface of the recess 14 f on the first structural body 11 side.

In the first modification, the other end 16 b of the stopper 16 has an opening 16 b - 1 , and a protrusion 14 g inserted into the opening 16 b - 1 is provided on the first structural body 11 side of the fourth structure 14 . A gap GP1 is provided between the opening 16b-1 and the protrusion 14g. The size of the gap GP1 is, for example, the size of the gap GP or less. Therefore, when a torque larger than the allowable torque is applied to the torque sensor 10, the first strain sensor can be protected by the protrusion 14g coming into contact with the opening 16b-1 of the stopper 16. 19.

The stopper 17 of the second strain sensor 20 also has the same structure as the stopper 16 .

The same effects as those of the third embodiment can also be obtained by the above-mentioned first modification. Furthermore, according to the first modification, the first strain sensor 19 (the second strain sensor 20 ) can be further protected by the protrusion 14 g coming into contact with the opening 16 b - 1 of the stopper 16 .

FIG. 21 shows a second modification of the third embodiment.

In contrast to the third embodiment including the stoppers 16 and 17, the second modification further includes four stoppers 16-1, 16-2, 17-1, and 17-2. The structures of the stoppers 16-1, 16-2, 17-1, and 17-2 are the same as the stoppers 16 and 17.

The same effects as those of the third embodiment can also be obtained by the second modification. Furthermore, according to the second modification, since the number of stoppers is larger than that in the third embodiment, the first strain sensor 19 and the second strain sensor 20 can be protected even more.

In addition, the present invention is not limited to the above-mentioned embodiments as it is, and in the implementation stage, the constituent elements can be modified and embodied within the scope that does not deviate from the gist of the invention. In addition, various inventions can be formed by appropriately combining the plurality of constituent elements disclosed in each of the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. In addition, components covering different embodiments may be appropriately combined. industrial availability

The torque sensor of this embodiment can be applied to a joint of a robot arm, for example.

10,30,60:Torque sensor 11: The first structure 11-1,12-1,14g:Protrusion 12:Second structure 12a: Hollow part 13:The third structure 14:The fourth structure 14a: 1st connection part 14b: 2nd connection part 14c: 3rd connection part 14d: 4th connection part 14e,16b-1: opening 14f,15f: concave part 15:The fifth structure 16,17,16-1,16-2,17-1,17-2: block 16a: One end 16b: the other end 18: cover 19,61: 1st strain sensor 20,62: 2nd strain sensor 21,22: Flexible substrate 41,63: Strain body 50:Bridge circuit 51,52,53,54: Strain gauge AR1, AR2: area CG:face CT:Central Department DG1, DG2: diagonal Fx, Fy, Fz, Mx, My: directions other than torque GND: ground GP, GP1: gap R1, R2, R3, R4: resistance value H:Thickness HS1, HS2: High rigidity part L1,L2,L11,L12: length LS1, LS2: low rigidity part Mz: Torque direction N1-N1, N2-N2, N3-N3, N4-N4: shaft OP: operational amplifier Op: action point W1,W2,W3: Width Vo:power supply Vout, Vout+, Vout-: output voltage

FIG. 1 is a plan view showing a torque sensor applicable to each embodiment.

FIG. 2 is a plan view showing a part of FIG. 1 removed.

FIG. 3 is a plan view showing the first embodiment with part of FIG. 2 removed;

FIG. 4 is a perspective view of FIG. 3 .

FIG. 5 is an enlarged plan view of part A indicated by a dotted line in FIG. 3 .

FIG. 6A is a plan view for explaining the operation when a force in the torque (Mz) direction is applied to the torque sensor shown in FIG. 5 .

FIG. 6B is a side view for explaining the operation when a force in a direction other than torque (Fz, Mx) is applied to the torque sensor shown in FIG. 5 .

FIG. 7 is a perspective view showing the structure shown in FIG. 5 .

FIG. 8A is a cross-sectional view along line VIIIA-VIIIA shown in FIG. 7 , and is a diagram for explaining the cross-sectional secondary moment in directions other than torque (Fz, Mx).

FIG. 8B is a cross-sectional view along line VIIIB-VIIIB shown in FIG. 7 , and is a diagram shown for explaining the cross-sectional secondary moment in directions other than torque (Fz, Mx).

FIG. 8C is a diagram for explaining the second moment of cross section of a general structure.

FIG. 8D is a diagram for explaining the second moment of cross section of a structure different from FIG. 8C .

FIG. 8E is a diagram for explaining the secondary moment of the cross section in the torque (Mz) direction of FIG. 8A .

FIG. 8F is a diagram for explaining the secondary moment of the cross section in the torque (Mz) direction of FIG. 8B .

FIG. 8G is a diagram for explaining the second moment of cross section of a structure different from FIGS. 8C and 8D .

FIG. 8H is a diagram for explaining the positional relationship between the structure and the strained body.

FIG. 9 is a plan view showing a torque sensor according to a comparative example of the first embodiment.

FIG. 10A is a plan view for explaining the operation when a force in the torque (Mz) direction is applied to the torque sensor shown in FIG. 9 .

FIG. 10B is a side view for explaining the operation when a force in a direction other than torque (Fz, Mx) is applied to the torque sensor shown in FIG. 9 .

11 is a diagram showing distortion when the same force is applied in each axial direction of the torque sensor of the first embodiment and the torque sensor of the comparative example.

FIG. 12 is a diagram showing the second embodiment, and is a plan view showing the first strain sensor and the second strain sensor.

FIG. 13 is a circuit diagram showing an example of the bridge circuit of the first strain sensor.

14 is a diagram illustrating the behavior of the strain body when a force in the torque direction is applied to the torque sensor according to the second embodiment, and when a force in a direction other than the torque direction is applied. .

FIG. 15 is a diagram schematically showing a torque sensor according to a comparative example of the second embodiment.

FIG. 16 is a diagram showing the third embodiment, and is a plan view showing an enlarged portion of B shown in FIG. 1 .

FIG. 17A is a diagram showing the operation of the stopper, and is a diagram schematically showing a part of FIG. 16 .

FIG. 17B is a diagram showing the operation of the stopper that is different from that of FIG. 17A , and is a diagram schematically showing a part of FIG. 16 .

FIG. 18 is a diagram for explaining the relationship between the torque applied to the torque sensor and the operation of the stopper.

FIG. 19 is a graph showing the relationship between strain and stress of a strain gauge.

FIG. 20 is a diagram showing a first modification of the third embodiment, and is a partially enlarged plan view.

FIG. 21 is a plan view showing a second modification of the third embodiment.

10:Torque sensor

11: The first structure

12:Second structure

14:The fourth structure

14a: 1st connection part

14b: 2nd connection part

14c: 3rd connection part

14d: 4th connection part

14e:Opening part

14f: concave part

19: 1st strain sensor

L1,L2,L11,L12: length

W1, W2: Width

Claims (8)

A torque sensor, characterized by: Has: 1st structure; 2nd structure; A plurality of third structures connecting the aforementioned first structure and the aforementioned second structure; At least one fourth structure is provided between the aforementioned first structure and the aforementioned second structure; and A strain sensor is provided in the aforementioned fourth structure, The aforementioned fourth structure has: a first connection part provided on the first structure and connected to one end of the strain sensor; a second connection part provided on the second structure and connected to the other end of the strain sensor; and The third connection part and the fourth connection part are provided between the first connection part and the second connection part, and have lower torque than the rigidity in the torque direction of the first connection part and the second connection part. The directional rigidity has higher rigidity to forces in directions other than torque than the rigidity in the torque direction. A torque sensor, characterized by: Has: The ring-shaped first structure; The annular second structure is arranged concentrically with the first structure; A plurality of third structures connecting the aforementioned first structure and the aforementioned second structure; At least one fourth structure is provided between the aforementioned first structure and the aforementioned second structure; and A strain sensor is provided in the aforementioned fourth structure, The aforementioned fourth structure has: a first connection part provided on the first structure and connected to one end of the strain sensor; a second connection part provided on the second structure and connected to the other end of the strain sensor; and The third connection part and the fourth connection part are provided between the first connection part and the second connection part, and have lower torque than the rigidity in the torque direction of the first connection part and the second connection part. The directional rigidity has higher rigidity to forces in directions other than torque than the rigidity in the torque direction. The torque sensor of claim 1 or 2, wherein the length of the third connection part and the fourth connection part in the direction from the first structure toward the second structure is longer than the length of the third connection part. The length of the structure in the direction from the first structure toward the second structure is shorter. The torque sensor of claim 1 or 2, wherein the third connection portion and the fourth connection portion intersect with the direction from the first structure toward the second structure and are along the first structure. The width in the plane direction is narrower than the width of the third structure in the direction crossing the direction from the first structure toward the second structure and along the plane direction of the first structure. The torque sensor of claim 1 or 2, wherein the first connection portion and the second connection portion intersect with the direction from the first structure toward the second structure and are along the first structure. The width in the direction of the plane is greater than the width of the third connecting portion and the fourth connecting portion in a direction that intersects the direction from the first structure toward the second structure and is along the plane of the first structure. The width is wider. The torque sensor of claim 1 or 2, wherein the first connecting portion and the second connecting portion intersect with the direction from the first structural body toward the second structural body and intersect with the direction of the first structural body. The thickness in the direction in which the planes intersect is greater than the thickness in the direction in which the third connecting portion and the fourth connecting portion intersect the direction from the first structure toward the second structure and intersects with the plane of the first structure. The thickness is thinner. The torque sensor of claim 1 or 2, wherein Js represents the cross-sectional secondary moment when a force in the torque direction is applied to the first connection part, and Jw represents the application of a force in the torque direction. The second moment of cross-section when a force other than the torque direction is applied to the first connection part is expressed as Is, and the second moment of cross-section is expressed as Iw when a force other than the torque direction is applied to the first connection part. When a force other than the moment direction is applied to the third connection part and the fourth connection part, the second moment of section is obtained, Js, Jw, Is, and Iw satisfy the following mathematical relationship: Js/Jw>Is/Iw. The torque sensor of claim 1 or 2, wherein the fourth structure has a recess in which the strain sensor can be disposed, and the surface of the strain sensor is consistent with a surface including the center of gravity of the structure, and the The structure is a structure formed of the first structure, the second structure, a plurality of the third structures, and at least one fourth structure.

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